Players: 2 (Online only, no split screen. Can choose to make other player slot a private slot)Online Trophies: Yes, all must be done online with 1 other playerOnline Pass Required for 100%: No, but purchase of DLC content from PS Store is required. [NORTH AMERICA PRICE] $3.99 for individual packs, $9.99 for all 4 packs.Estimated Time to 100%: 2-4 hours (Depending on skill and speed at killing enemies) if playing with a booster, 10+ if playing with strangersMinimum Playthroughs: 10-40 matchesDifficulty Trophies: NoneStackable Difficulty Trophies: N/ACollectible Trophies: No Missable Trophies: None

When killing enemies, keep an eye on your opponent's health gauge at the top right of the screen. If they are running low on health, send enemies their way to make it harder for them to survive.

When killing enemies, you build up a combo chain for killing enemies in rapid succession. At any time, before your combo reaches 30, stop moving and tap to send all the amount of enemies in your current combo to your opponent's map. Doing this can also get you out of a tight space, as the same amount of enemies you send over will be removed from your map.

Before starting the game, either creating a lobby or joining one, you have the option to select/purchase/equip a skill set. Unlike the campaign, you can only equip 1 skill in your skill set, but you still have 8 total skill set slots. Also unlike the campaign, you now have access to new skills, along with some familiar skills. Any skills that are in the campaign that you have unlocked using skill points can are unlocked here as well. However the new skills must be unlocked in this menu for use only in the DLC game modes.

Enemies will spawn on both your and your opponent's map naturally. When you or your opponent sends enemies over, that player must deal with the naturally spawning enemies along with the sent-over enemies.

There are item boxes all around. If you can, break them to snag whats inside, ranging from skill points to health herbs to ammo. Enemies will also drop such items when defeated. There are also environmental objects, such as red flammable barrels that explode in a big fireball when shot. use these to your advantage and achieve higher kill-chains much easier.

At some point, your opponent might send over a massive amount of enemies at one time. This puts you in "No Hope" mode, which is the game basically saying "You're screwed." This does not mean it's automatically game over. Just shoot who you can, run and avoid being hit. Enemies killed during this time give you a bigger score multiplier.

Higher combo chains mean tougher enemies sent to your opponent when your combo chain ends. If you can, always wait for a chain between 20 or 30 in order to send the toughest enemies to your opponent's map.

Be aware, there are extra Stages that are available for purchase on the PlayStation Store. These extra Stages can be played in Onslaught, along with the other DLC packs and Mercenaries, but they cannot be used to obtain the TAKE THE STAGE trophy

If you are playing with a booster, you can really choose whichever trophy you want to go and whenever you want to.
Keep in mind that DLC stages purchased through the Playstation Store can be used to obtain all of these trophies, so find one that suits your needs best and play on that map.
Here's what I would recommend though:

STEP 1) Earn the Kill Or Be Killed trophy in Urban Chaos
STEP 2) Defeat your opponent twice with enemies you sent over to them in the remaining two main stages, once each, to earn the TAKE THE STAGE trophy. At this time you will probably get the KILLER COMBO trophy.
STEP 3) If you didn't get it in Step 2, get the KILLER COMBO trophy while going for the YOU ARE S.O.L. trophy. You may also get the SURROUNDED ON ALL SIDES trophy during this step.
STEP 4) At this point SURROUNDED ON ALL SIDES should be your last trophy, though if your opponent was great at surviving for long periods of time against massive amounts of enemies, you may be very close to or have already gotten this trophy. If you haven't gotten it already, you can grind your way to it now and enjoy your new 100%

Surrounded on all SidesSend 2,000 enemies to your opponent's map.

To send enemies to your opponent's map, you must kill enemies in rapid succession to create a kill-combo chain. Once you have a combo chain going, at anytime, you can stop moving at tap to end your chain and send enemies to your opponent's map based on what your kill-chain combo number was. You can also wait until you have reached a Killer Combo (30 kills) to have the game automatically send those 30 enemies to your opponent.
For this trophy, you will need to do some grinding, though not very much.

All you need to do is use or Killer Combos to send enemies to your opponent. Just keep killing and tapping or reach a Killer Combo un til you have sent over 2000 total enemies. You do not have to do this in one match, and are almost guaranteed to not be able to do this in one match.

To check your progress on this, you can either go to the "Records" section in the main menu and scroll to the right, or you can also enter the "Dog Tags" section and scroll to find the "Mighty Spammer" title. When you achieve this trophy, you will also max out this title.

Killer ComboAchieve a 30-combo chain.

Combo chains can be achieved by killing enemies in rapid succession. You don't have to kill them one right after another, as the game gives you a good few seconds to achieve your next kill before the combo chain ends. You'll notice that if you have a combo chain in progress and you don't kill an enemy for a few seconds, your combo number will begin to flash, flashing faster and faster as it runs out of time.

For this trophy, you need to kill 30 enemies, at which point your combo will automatically end itself and send 30 enemies to your opponents map.
Do not press at any time during your combo, otherwise you will end the combo manually and send enemies to your opponent based on whatever your combo number was.

You are S.O.L.Defeat your opponent 10 times with enemies you sent.

For this trophy, you must build up a kill-chain in order to send enemies to your opponent's map. Achieving higher combo chains sends tougher enemies to your opponent. The more you send over, the better your chances of killing your opponent with those sent enemies.

For this trophy, your opponent must be killed by an enemy. They cant be killed by any environmental object such as red flammable barrels. I do not know, however, if it does not count if your opponent is killed by an enemy that spawns on your opponents map, but is not sent by you. Anytime my opponent died by an enemy, it was because of an enemy I sent.

Kill or be KilledWin while in the dying state.

This trophy is so much easier when playing with a booster.
The dying state is when you are lying on the ground on your back, screen somewhat blacked out around the edges and tinted red in the middle. There is also a "recovery" bar in the middle that fills from left to right. This is a timer, telling you how long until you are able to get back up and resume the fight on your feet. You can kill enemies with the gun you had equipped before you went down while in this state, but be cautioned, because if you get damaged once during this state, you die instantly.
WHEN PLAYING WITH A BOOSTER: as soon as the match starts, both you and your opponent throw a hand grenade on the ground and then both stand on top of the grenade to have you enter the dying state. all your opponent has to do is get hit by an enemy while your still in the dying state. You, however must avoid being hit by an enemy or else you will die. Be sure to equip a strong gun before entering the dying state, such as a shotgun, because you cannot switch weapons once dying.
WHEN PLAYING WITH STRANGERS: survive as long as you can until your opponent enters the dying state. you must then enter the dying state too, and hope that you do not get injured again, while your opponent does get injured again, before recovering. This may take many matches, as you probably won't have that many opponents enter the dying state. If you still don't have a booster for this, then keep finding matches and hope to get lucky.